Method and apparatus for transporting and steering a heavy load

ABSTRACT

A method and apparatus for transporting heavy machinery, equipment or other heavy loads from one location to another, whereby the apparatus may be constructed as a walking machine including a plurality of lifting assemblies operative to lift the load above the supporting surface and then move the load relative to the supporting surface by transporting the load via rollers or tracks in the walking machines. In one example, the lifting assemblies are provided with separate longitudinal and lateral drive mechanisms independently operative for translating the load in either or both longitudinal and lateral directions.

RELATED APPLICATION DATA

This application is a nonprovisional of and claims the benefit under 35U.S.C. § 119(e) of U.S. Provisional Patent Application No. 62/719,343,filed Aug. 17, 2018, the disclosure of which is incorporated byreference herein in its entirety.

BACKGROUND

The field of the present invention is related to a class oftransportation machines commonly referred to as “walking machines,”which are large, typically non-wheeled, power-driven structures operablefor transporting heavy loads (e.g., loads weighing upwards of severalthousand tons) over a road or other ground surface. These machines, andthe heavy substructures in themselves, are fabricated from steel andother high-strength materials and find particular use in carrying andsequentially transporting large structures. For example, a walkingmachine may be used to transport oil drilling rigs and position themover a drilling well bore in a new field undergoing exploration for oil,or over existing well bores in an old, established field.

Instead of using ground-contacting wheels to move the heavy loads, thesewalking machines typically comprise a plurality of lifting assembliesthat use hydraulic lift cylinders to lift the load above the supportingsurface and then move the load relative to the supporting surface bytransporting the load via rollers or tracks in the walking machines.

In order to position the oil rig or other heavy load in a preciseposition, these walking machines may be provided with a steeringmechanism whereby the walking machine unit may be rotated or steered toa desired position. U.S. Pat. No. 6,581,525, the disclosure of which isincorporated by reference herein, provides additional details relatingto walking machine systems and methods for moving heavy loads. The '525patent also discloses a steering system for a walking machine in which asubstructure of the walking unit may be disengaged and rotated relativeto its upper structure thus repositioning the substructure for travel ata desired steered angle. U.S. Published Application No. 2017/0022765discloses a walking machine unit with an improved steering system. Thepresent inventor has recognized that these steering systems have roomfor improvement.

SUMMARY

The present disclosure is directed to apparatus and methods fortransporting heavy machinery, equipment or other heavy load from onelocation to another, whereby the apparatus is constructed to transportthe load in multiple directions in order to move the load in a desiredpath to a set position. An example embodiment is directed to a walkingmachine comprising a plurality of lifting assemblies operative to liftthe load above the supporting surface and then move the load relative tothe supporting surface (e.g., the road or other ground surface) bytransporting the load via rollers or tracks in the walking machines. Inone embodiment, the lifting assembly may include transport mechanismsoperative for transporting the load in multiple directions—in oneexample both a first direction (e.g., longitudinally) and a seconddirection (e.g., laterally)—so that lifting assemblies may be driven orsteered in a desired walking direction or along a desired directionalpath. In another example embodiment, a walking machine is provided withan improved re-centering system whereby the bad being transported can bequickly and efficiently re-centered after each movement to ensure thatthe load is properly centered and stabilized before the load issubsequently moved. Additional aspects and advantages will be apparentfrom the following detailed description of example embodiments, whichproceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of an example walking machine system formoving a large support structure, such as an oil rig.

FIG. 2 is a partial view of the walking machine system of FIG. 1 withtwo walking machine units in position underneath and connected to theoil rig.

FIGS. 3-7 are partial views of the walking machine system of FIG. 1illustrating an example operation of the walking machine units.

FIG. 8 is a top plan view of a walking machine system according to anexample embodiment, with four walking machine units, one disposed ateach of the four corners of the oil rig.

FIGS. 9-12 are each a top plan view of one side of the walking machinesystem of FIG. 8 , illustrating two walking units. In FIG. 9 , thewalking units are in a first longitudinal position and central lateralposition; in FIG. 10 , the walking units are in a forward extendedposition and central lateral position; in FIG. 11 , the walking unitsare in the first (rearward) longitudinal position and right side lateralposition; in FIG. 12 , the walking units are in the first (rearward)longitudinal position and left side lateral position.

FIG. 13 is a top isometric view of the walking machine units of FIG. 9 .

FIGS. 14 and 15 are top right and left rear isometric views of a walkingmachine unit according to one embodiment.

FIG. 16 is a partially exploded isometric view of the walking machineunit of FIGS. 14 and 15 .

FIG. 17 is a top isometric view of a roller assembly of the walkingmachine unit of FIG. 14 .

FIG. 18 is a cross-section view illustrating internal components of theroller assembly.

FIGS. 19A, 19B, and 19C are partially exploded views of a walkingmachine unit according to another embodiment.

FIGS. 20A, 20B, and 20C illustrate views of an embodiment of a centeringfixture or frame.

FIGS. 21A, 21B, and 22 illustrate an embodiment of a centering pivot armaccording to one embodiment.

FIG. 23 illustrates an embodiment of a walking machine unit according toone embodiment.

FIGS. 24A and 24B are schematic illustrations representing an exampleoperation of the centering pivot arm of FIG. 21 for realigning a footsection of the walking machine unit of FIG. 23 .

FIGS. 25A, 25B, 25C, 25D, 25E, 25F, and 25G collectively illustrate awalking cycle of the walking machine unit in accordance with oneembodiment.

FIG. 26 illustrates a perspective view of a walking machine unitaccording to another embodiment.

FIG. 27 is a partially exploded view of the walking machine unit of FIG.26 .

FIG. 28 illustrates an embodiment of a centering fixture or frame of thewalking machine unit of FIG. 26 .

FIG. 29 illustrates an example embodiment of an alignment plate of thewalking machine unit of FIG. 26 .

FIG. 30 is a top perspective view of a walking machine system accordingto an example embodiment, with four walking machine units, one disposedat each of the four corners of a rig structure.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the drawings, this section describes particularexample embodiments and their detailed construction and operation. Tofacilitate description, any element numeral representing an element inone figure will be used to represent the same element when used in anyother figure. The embodiments described herein are set forth by way ofillustration only and not limitation. It should be recognized in lightof the teachings herein that there is a range of equivalents to theexample embodiments described herein. Notably, other embodiments arepossible, variations can be made to the embodiments described herein andthere may be equivalents to the components, parts, or steps that make upor augment the described embodiments.

The described features, structures, characteristics, and methods ofoperation may be combined in any suitable manner in one or moreembodiments. In view of the disclosure herein, those skilled in the artwill recognize that the various embodiments can be practiced without oneor more of the specific details or with other methods, components,materials, or the like. In other instances, well-known structures,materials, or methods of operation are not shown or not described indetail to avoid obscuring more pertinent aspects of the embodiments.

FIGS. 1-7 are a series of schematic drawings illustrating an examplewalking machine system for moving an oil rig 10 (or other large supportstructure) along a ground surface 5. The oil rig 10 is supported at theground surface 5 by a plurality of support legs 55 attached to thebottom support structure 50. The walking machine system includes a setof four lifting assemblies (or lifting machine units), with a liftingassembly or unit arranged in position proximate each of the corners ofthe oil rig 10. Two lifting assemblies 100, 102 are visible in FIGS. 1-7and the other two lifting assemblies 104, 106 are illustrated in FIG. 8described below. The lifting assemblies 100, 102, 104, 106 may besupported via a longitudinal beam (as shown) or other configuration suchas via a horizontal beam. Though four lifting assemblies are shown, thesystem may include additional lifting assemblies.

Operation of the lifting assemblies 100, 102, 104, 106 is now describedwith respect to a first lifting assembly 100 with the understanding thatthe same description applies equally to lifting assemblies 102, 104,106. For initial installation, the lifting assembly 100 is set inposition on the ground as in FIG. 1 with its lifting cylinder retractedand not contacting the oil rig 10. The lifting cylinder of the liftingassembly 100 is raised partway as in FIG. 2 to contact the oil rigsupport beam/structure 50. The lifting assembly 100 is then connected tothe beam/structure 50 via a suitable fastener mechanism (e.g.,attachment bolts are visible in FIG. 2 ) or other suitable attachments.The lifting cylinder is then retracted, thereby lifting the lowerstructure or jack pad of the lifting assembly 100 off the ground (due toits attachment to the support beam 50 of the oil rig 10), and then thelifting assembly lower structure and foot pad are driven forward by afirst push-pull mechanism to the forward position as in FIG. 3 . Thelifting cylinder is then partially extended, lowering the liftingassembly lower structure and jack pad to the ground as shown in FIG. 4 .The lifting cylinder is then raised to the extended position therebylifting the support structure 50 and support legs 55 of the oil rig 10off the ground as in FIG. 5 . Once the oil rig 10 is lifted, the liftingassembly lower structure (the foot) is driven rearward by the firstpush-pull mechanism to the rearward position, thereby moving the rig 10forward as in FIG. 6 . The lifting cylinder is then retracted, liftingthe assembly lower structure off the ground as in FIG. 7 , after whichthe assembly lower structure may then be driven forward to the positionas in FIG. 3 . The process steps are then repeated.

In one embodiment, a second push-pull mechanism, operating separately orin combination with the first (longitudinal) push-pull mechanism,provides for lateral drive motion. In any event, the second (lateral)push-pull mechanism is operable independently from the first(longitudinal) push-pull mechanism enabling for lateral motion with orwithout longitudinal motion.

Further details of the lifting assembly and push-pull mechanisms willnow be described. FIG. 8 illustrates a top plan view of the walkingmachine system comprised of the four walking machine units 100, 102,104, 106 with the oil rig 10 removed and showing support structure 50.The walking machine units 100, 102, 104, 106 in FIG. 8 are illustratedin a first longitudinal (non-extended) travel position, and laterallycentered.

FIGS. 9-13 illustrate one side of the walking machine system and two ofthe walking machine units 100, 102 in various positions. In FIGS. 9 and13 , the walking machine units 100, 102 are illustrated in the firstlongitudinal, non-extended or rearward, travel position, and laterallycentered (similar to FIG. 8 ). The isometric view of FIG. 13 furtherillustrates the forward walking machine unit disposed within the crossbeams 52, 54 of the support structure 50 and also illustrates the rearlifting assembly with cross beams of the support structure 50 removed.In FIG. 10 , the walking machine units 100, 102 are illustrated in thesecond longitudinal, forward-extended, travel position, and laterallycentered. In FIG. 11 , the walking machine units 100, 102 areillustrated in the first longitudinal, non-extended or rearward, travelposition, and laterally to the right side. In FIG. 12 the walkingmachine units 100, 102 are illustrated in the first longitudinal,non-extended or rearward, travel position, and laterally to the leftside. Though not shown, the walking machine units may be translated intothe second longitudinal, forward-extended, travel position, andlaterally translated to the left or right. The following sectionsdescribe additional details relating to the walking machines units 100,102, 104, 106 and their various components for supporting the movementof the overall walking machine system.

FIGS. 14-16 collectively illustrate details of the walking machine unit100 according to an embodiment. As noted previously, it should beunderstood that any description relating to walking machine unit 100also applies to walking machine units 102, 104, 106, or any otherwalking machine units used in the walking machine system. With generalreference to FIGS. 14-16 , the walking machine unit 100 comprises a footplate assembly or foot section 110, an upper roller guide assembly 200(with lateral drive), a longitudinal drive assembly 300, and a liftassembly 400. With particular reference to FIG. 14 , the followingprovides additional details of the structure and drive system for thelateral translation mechanism according to one embodiment.

With reference to FIG. 14 , the foot section 110 comprises a foot plate111 that contacts the ground surface during a walking motion of thewalking machine unit 100. The foot section 110 comprises a foot plate111 of generally rectangular shape that may include slightly curvedfront and rear ends. In other embodiments, the foot plate 111 mayalternatively be another suitable shape such as oblong or circular, theelongated rectangular structure may enable the walking machine unit 100to have a longer longitudinal travel stroke with a solid/stablefootprint. The foot section 110 includes a plurality of retainer barssecured to and arranged about the upper surface of the foot plate 111,including retainer bars 112 a, 112 b, 112 c on one lateral side (seeFIG. 14 ), retainer bars 112 d, 112 e, 112 f on the opposite side (seeFIG. 15 ), and additional retainer bars on the front and rear sides (notshown) of the foot plate 111.

A slide plate 180 (see FIG. 16 ), which may be constructed of stainlesssteel, is disposed flat on a substantially central portion of the footplate 111 nesting between the retainer bars 112. The slide plate 180thus remains free-floating, but its lateral and longitudinal position ismaintained centrally within and flat against the foot plate 111.Alternatively the slide plate 180 may be attached to the foot plate 111such as by welding or connectors (e.g., screws or bolts), but thefloating construction may better manage expansion/contraction issues dueto different expansion coefficients of the steel types and may alsoprovide for easier construction and/or repair/replacement or allow forexpansion of a non-composite plate configuration due to deflection ofthe foot plate/slide.

A low friction plate 190 comprising a flat bushing is disposedunderneath the lower surface of the roller guide assembly 200 to providefor a low friction slide surface between the roller guide assembly 200and the slide plate 180. The low friction plate 190 may be made of nylon(e.g., a lubricant filled plastic such as Nylatron® plastic availablefrom Quadrant EPP USA, Inc. of Reading, Pa.), PTFE, bronze or othermetal, or other suitable plate/sheet material or coated plate. In otherembodiments, a lubrication (e.g., grease) may be applied to the slideplate 180. Alternately, the positions of the slide plate 180 and the lowfriction plate 190 may be reversed. Alternately, instead of a lowfriction slide surface configuration, roller bearings or other suitablebearing or roller assembly system may be employed to provide for lowfriction lateral movement.

With collective reference to FIGS. 14-16 , the roller guide assembly 200comprises a main or bottom plate 210 and first and second roller supportsides. The first roller support side comprises a top plate 230 and avertical wall 234 forming a generally I-beam cross-section with thebottom plate 210. The top plate 230, vertical wall 234 and bottom plate210 collectively form an open channel or track 235. The top plate 230 issecured to the vertical wall 234 and the bottom plate 210 via a seriesof eight stiffening ribs, two of which are designated by elementnumerals 232 a and 232 b (see FIG. 14 ). Similarly, the second rollersupport side comprises a top plate 220 and a vertical wall 224 forming agenerally I-beam cross-section with the bottom plate 210. The top plate220, vertical wall 224 and bottom plate 210 form an open channel ortrack 225. The top plate 220 is secured to the vertical wall 224 and thebottom plate 210 via a series of eight stiffening ribs, two of which aredesignated by element numerals 222 a and 222 b.

Guide tubes 160, 170 are attached to the bottom plate 210 on oppositelongitudinal sides. The guide tube 160 includes an attachment bracket164, and the guide tube 170 includes an attachment bracket 174. Theroller guide assembly 200 is mounted to the foot plate 111 via the guidetubes 160, 170 to allow lateral movement. Guide bars 161, 171 aredisposed on opposite longitudinal sides of the foot plate 111. Guide bar161 is secured to the foot plate 111 via brackets 162, 166, and guidebar 171 is secured to the foot plate 111 by brackets 172, 176. Brackets144, 154 are also secured onto the foot plate 111 for attachment to thelateral drive cylinders 140, 150. A cylindrical sleeve or bushing 160 aof low friction material (e.g., nylon or other suitable material) may beinstalled within the guide tube 160 and around the guide bar 161, and acylindrical sleeve or bushing 170 a of low friction material issimilarly installed within the guide tube 170 and around the guide bar171.

The lateral drive force is provided by lateral drive cylinders 140, 150attached between the roller guide assembly 200 and the foot plate 111.The drive cylinder 140 is connected at one end 141 to the bracket 164via a pin 149, and at its second end 145 on piston shaft 142 to thebracket 144 on foot plate 111 via pin 146. Similarly on the other side,the drive cylinder 150 is connected at one end 151 to the bracket 174via a pin 159, and at its second end 155 on piston shaft 152 to thebracket 154 on foot plate 111 via pin 156. Alternate lateral drive forcemay be provided by any suitable drive mechanism including thepiston/cylinder drive (as illustrated), jack screw drive, rack andpinion assembly, chain and sprocket drive, gear drive, electric motor,or other drive systems.

The entire lift mechanism 400 and roller guide assembly 200 thus areable to be translated laterally, driven by the hydraulic drive cylinders140, 150, via the interaction of slide plates 180 and friction plate 190described previously with reference to FIG. 16 . Further detailsrelating to the lift assembly 400 and roller guide assembly 200 foraccommodating lateral translation movement are described in U.S. Pat.App. No. 2017/00227695, the disclosure of which is incorporated byreference herein.

With collective reference to FIGS. 16-18 , the following sectionsdescribe details relating to the longitudinal drive assembly 300 foraccommodating longitudinal movement of the walking machine. Asillustrated in the figures, the longitudinal drive assembly 300comprises a roller assembly 305 and drive cylinder 310. With particularreference to the cross-section of FIG. 18 , the roller assembly 305includes a roller housing section 322 of generally rectangular box shapeformed with two internal channels 331, 335 for accommodating the rollers334, 336. The first internal channel 331 is formed by side walls 326 a,326 b, with roller plate 334 attached to the side walls 326 a, 326 b.The second internal channel 335 is formed by side walls 324 a, 324 b,with roller plate 336 attached to the side walls 324 a, 324 b. Therollers 334, 336 may comprise chain roller bearings such as availablefrom Hilman Incorporated of Marlboro, N.J. Other low friction or reducedfriction systems may be employed for the longitudinal drive assembly 300in place of the roller assembly 305, such as other types of bearings,slide surfaces (e.g., a plate bushing), or other suitable construction.

With particular reference to FIG. 17 , the roller assembly 305 includesa drive connection bracket assembly including a U-shaped upper bracket370 and a U-shaped lower bracket 380. An attachment bracket 374 isdisposed on the end of the upper bracket 370. A hole 372 is disposed inthe end of the upper bracket 370 for connection to the longitudinaldrive cylinder 310. The longitudinal drive cylinder 310 is disposedwithin a central channel or opening between the (inner) side walls 326b, 324 b and extends into the open inner portion of the U-shapedbrackets 370, 380. As illustrated in FIGS. 15 and 16 , the longitudinaldrive cylinder 310 is connected at its shaft end 312 to bracket 240 onthe upper roller guide assembly 200 via a pin 313, and on the other end314 to upper and lower brackets 370, 380 via a pin 315 extending througha hole (not shown) formed in the upper bracket 370 and a correspondinghole (not shown) in the lower bracket 380.

It should be understood that although the longitudinal drive mechanismis shown for example as a hydraulic drive system comprising thelongitudinal drive cylinder 310, other types of longitudinal drivemechanisms may be employed such as the piston/cylinder drive (asillustrated), jack screw drive, rack and pinion assembly, chain andsprocket drive, gear drive, electric motor, or other drive systems.

FIGS. 19A, 19B, and 19C collectively illustrate another embodiment of awalking machine unit 500 (see FIG. 19C) that can be used in conjunctionwith the walking machine system. The walking machine unit 500 mayinclude some of the same features and characteristics as the walkingmachine unit 100 described previously with reference to FIGS. 14-18 .Accordingly, certain features of the walking machine unit 500 may bedescribed briefly herein and other features may not be further discussedin detail to avoid obscuring more pertinent features of the embodiment.The following section provides a brief description of the walkingmachine unit 500 for ease of reference followed by a more detaileddescription of particular features of the walking machine unit 500.

Briefly, the walking machine unit 500 includes a foot section 510 with afoot plate 511 that contacts the ground surface during a walking motionof the walking machine unit 500. Similar to foot plate 111, the footplate 511 may have a generally rectangular shape with curved ends, ormay have any other suitable shape to support movement of the walkingmachine unit 500. The foot section 510 includes a plurality of retainerbars secured to and arranged about the upper surface of the foot plate511, including retainer bars 512 a, 512 b, 512 c, 512 d on one lateralside, retainer bars 512 e, 512 f, 512 g, 512 h on the opposite side, andadditional retainer bars 512 i, 512 j on a front foot plate section 511a, and retainer bars 512 k (second retainer obscured from view) on arear foot plate section 511 b.

Slide plates 580 a, 580 b, which may be constructed of stainless steel,are disposed flat on the foot plate 511, with one slide plate 580 apositioned against the front foot plate section 511 a, and the otherslide plate 580 b positioned against the rear foot plate section 511 b,where the slide plates 580 a, 580 b nest between the respective retainerbars 512 a-512 k on the foot plate 511. The slide plates 580 a, 580 bthus remain free-floating, but their respective lateral and longitudinalposition is maintained centrally within and flat against the foot plate511. Alternatively the slide plates 580 a, 580 b may be fixedly attachedto the foot plate 511 such as by welding or connectors (e.g., screws orbolts), but the floating construction may better manageexpansion/contraction issues due to different expansion coefficients ofthe steel types and may also provide for easier construction and/orrepair/replacement or allow for expansion of a non-composite plateconfiguration due to deflection of the foot plate/slide.

The walking unit 500 includes a set of low friction plates 590 a, 590 beach comprising a flat bushing, where the plates 590 a, 590 b aredisposed underneath the lower surface of the roller guide assembly 600to provide for a low friction slide surface between the roller guideassembly 600 and the slide plates 580 a, 580 b. As described previously,the low friction plates 590 a, 590 b may be made of nylon (e.g., alubricant filled plastic such as Nylatron® plastic available fromQuadrant EPP USA, Inc. of Reading, Pa.), PTFE, bronze or other metal, orother suitable plate/sheet material or coated plate. In otherembodiments, a lubrication (e.g., grease) may be applied to the slideplates 580 a, 580 b. Alternately, the positions of the slide plates 580a, 580 b and the low friction plates 590 a, 590 b may be reversed.Alternately, instead of a low friction slide surface configuration,roller bearings or other suitable bearing or roller assembly system maybe employed to provide for low friction lateral movement.

The roller guide assembly 600 is similar to the roller guide assembly200 discussed previously with reference to FIGS. 14-16 . Briefly, theroller guide assembly 600 comprises a main or bottom plate 610, a firstroller support side 620, and a second roller support side 630. Theroller support sides 620, 630 each include vertical walls (not numbered)forming a generally I-beam cross-section with the bottom plate 610.Similar to the roller guide assembly 200, the roller guide assembly 600includes a plurality of stiffening ribs (not numbered) extending fromthe bottom plate 610 to strengthen the roller support sides 620, 630.

Similar to the walking machine unit 100, the lateral drive force for thewalking machine unit 500 is provided by lateral drive cylinders 540, 550(see FIG. 19C) attached between the roller guide assembly 600 and thefoot plate 511. The drive cylinder 540 is connected at one end to thebracket 564 via a pin 549, and at its second end to the bracket 544 onfoot plate 511 via pin 546 (see FIG. 19B). The drive cylinder 550 isconnected in a similar arrangement to the brackets 554, 574 along theother end of the foot plate 511. Alternate lateral drive force may beprovided by any suitable drive mechanism including the piston/cylinderdrive (as illustrated), jack screw drive, rack and pinion assembly,chain and sprocket drive, gear drive, electric motor, or other drivesystems.

The following sections describe details relating to the longitudinaldrive assembly for accommodating longitudinal movement of the walkingmachine. With particular reference to FIG. 19C, the longitudinal driveassembly comprises a roller assembly 705 and a pair of drive cylinders710, 712. The roller assembly 705 includes a roller housing section 720of generally rectangular box shape formed with two internal channels(not shown) for accommodating a set of rollers 730 (see FIG. 19B). Therollers 730 may comprise chain roller bearings or other low friction orreduced friction systems such as bearings, slides surfaces, or othersuitable construction operable to facilitate movement of the rollerassembly 705. In a similar fashion as the roller assembly 305, theroller assembly 705 is positioned on the roller guide assembly 600between the roller support sides 620, 630 to accommodate longitudinalmovement.

The drive cylinders 710, 712 are attached to the roller support sides620, 630 of the roller guide assembly 600 and also attached to theroller assembly 705 to drive the walking machine unit 500 in alongitudinal direction. With reference to FIG. 19A, the drive cylinder710 is attached along one end to the roller support sides 630 viaopening 714 formed thereon, and the drive cylinder 712 is attached alongone end to the roller support sides 620 via opening 716 formed thereon.The drive cylinder 710 is also attached along another end to an opening718 formed on a flange 722 of the roller housing section 720, and thedrive cylinder 712 is also attached along another end to an opening 724formed on the flange 722 of the roller housing section 720. It should beunderstood that although the longitudinal drive mechanism is shown forexample as a hydraulic drive system comprising the longitudinal drivecylinders 710, 712, other types of longitudinal drive mechanisms may beemployed such as the piston/cylinder drive (as illustrated), jack screwdrive, rack and pinion assembly, chain and sprocket drive, gear drive,electric motor, or other drive systems.

With particular reference to FIGS. 20-24 , the following sectionscollectively describe components of the walking machine unit 500designed to center or accommodate for misalignment during the driveoperation when moving a load using the walking machine system. FIGS.20A, 20B, and 20C collectively illustrate an embodiment of a centeringfixture (or frame) 800 of the walking unit 500. With reference to FIGS.20A, 20B, and 20C, the centering fixture 800 includes a first supportarm 802 and an opposite second support arm 804. The fixture 800 furtherincludes a second pair of support arms 806, 808 each extendingtransversely across from the first support arm 802 to the second supportarm 804 along top and bottom ends to form a generally square-shaped orrectangular-shaped structure for the centering fixture 800. It should beunderstood that in other embodiments, the fixture 800 may have a profileother than a square or rectangular shape.

The fixture 800 includes a first mounting plate 810 positioned betweenthe first and second support arms 802, 804 and adjacent the arm 806,where the first mounting plate 810 is coupled to the arms 802, 804, 806.Similarly, the fixture 800 includes a second mounting plate 812 ispositioned between the first and second arms 802, 804 and adjacent thearm 808 and coupled thereto. The mounting plates 810, 812 each includeone or more fastener openings 814 (e.g., bolt holes) for receiving bolts816 (see FIG. 19C) therethrough to attach the centering fixture 800 tothe roller assembly 705 when the walking machine unit 500 is assembled.With reference to FIG. 20B, the centering fixture 800 includes anopening 818 disposed between the mounting plates 810, 812 and boundedbetween the support arms 802, 804. The opening 818 aligns with anopening 735 formed on the roller assembly 705 (see FIG. 19B) toaccommodate the lift cylinder 520 when the walking machine unit 500 isfully assembled.

With reference to FIG. 20A, the centering fixture 800 further includesone or more centering members or strike plates 820 supported thereon,the strike plates 820 each providing a contact area for an alignment orcentering pivot arm 828 of the walking machine unit 500 as furtherdescribed in detail below with reference to FIGS. 21-24 . Turning backto FIG. 20A, the strike plate 820 is substantially an L-shaped brackethaving a first surface 822 and a second surface 824 arranged generallyorthogonally to the first surface 822. In some embodiments, thecentering fixture 800 may include four strike plates 820, with onestrike plate 820 coupled to the arms 802, 806; one strike plate 820coupled to the arms 804, 806; one strike plate 820 coupled to the arms802, 808; and one strike plate 820 coupled to the arms 804, 808, asillustrated in FIG. 20B. In such embodiments, the first surface 822 ofthe strike plate 820 is arranged along a horizontal plane of thecentering fixture 800 and the second surface 824 arranged along avertical plane of the centering fixture 800, such that the strike plates820 each generally wrap around either the first and second support arms802, 804. In other embodiments, the centering fixture 800 may includeonly two strike plates, such as where the two strike plates 820supported on arm 806 are formed as a single, integral unit, and the twostrike plates 820 supported on arm 808 are formed as a single, integralunit.

In some embodiments, the centering fixture 800 may be made of a weldedsteel construction. Due to its weight, the centering fixture 800 may bedifficult to lift manually during the assembly process. Accordingly, insome embodiments, the centering fixture 800 may include a lift ring 826(e.g., a D-ring assembly) coupled to one or both arms 806, 808 to aid inlifting the centering fixture 800.

FIGS. 21A and 21B are a side elevation and top plan view, respectively,of a centering pivot arm 828 of the walking machine unit 500, and FIG.22 is an exploded view of the centering pivot arm 828. With collectivereference to these figures, the centering pivot arm 828 includes a firstpivot arm side plate 830 and a second pivot arm side plate 832, eachhaving a generally S-shaped curve construction. The centering pivot arm828 includes a jacking block 834 coupled along one end between the pivotarm side plates 830, 832, and further includes an adjustable bearingblock 836 coupled along an opposite end between the side plates 830,832. In addition, a stainless steel pin 838 extends between the sideplates 830, 832 and provides an attachment point of the centering pivotarm 828 to the hood assembly 900 (see FIG. 23 ).

With particular reference to FIGS. 21A and 21B, the adjustable bearingblock 836 includes at least one contact surface 840. Preferably, thecontact surface 840 is generally flat/planar to reduce bearing pressurein comparison to a round contact surface, but the surface can have anysuitable profile. Briefly, the adjustable bearing block 836 corrects forrotational misalignment of the foot, while the foot level contactsurface 842 helps ensure the foot is level and parallel to the ground.Additional information on the functionality of the centering pivot arms828, adjustable bearing block 836, and foot leveling contact surface 842is described in further detail with particular reference to FIGS. 23-25. In some embodiments, the adjustable bearing block 836 may be made ofan ultra-high molecular weight plastic or nylon material to provide somesliding contact and minimize wear. In other embodiments, the adjustablebearing block 836 may instead be a steel block (or other suitablemetal), or may be formed from a metal structure and include a plasticcontact surface.

With reference to FIGS. 23 and 24 , the following section provides ahigh-level description of the functionality of the centering pivot arms828. Although reference in the following description is made only to onecentering pivot arm 828, it should be understood that the walkingmachine unit 500 typically includes four pivot arms 828 (two on each ofa front side and a rear side of the machine walking unit 500) eachoperating in the same general fashion. Accordingly, it should beunderstood that the ensuing description applies equally to all suchpivot arms.

With collective reference to FIGS. 23 and 24 , the pivot arms 828 areused to re-align the foot section 510 relative to the hood assembly 900between movements of the load to maintain proper weight distribution ofthe load being moved. As illustrated in FIG. 23 , to properly align thefoot section 510, the foot leveling contact surface 842 of the centeringpivot arm 828 rests against the first surface 822 of the strike plate820 (supported on the centering fixture 800) to ensure that the footsection 510 is parallel to the ground when the foot section 510 israised. In addition, the adjustable bearing block 836 on the end of thecentering pivot arm 828 rests against the second surface 824 of thestrike plate 820 to correct any rotational misalignment of the footsection 510.

For example, with particular reference to FIG. 24A, when the footsection 510 is rotated in a counter-clockwise direction relative to acentral axis A extending through the centering fixture 800, theadjustable bearing block 836 a of a first centering pivot arm 828 a andthe adjustable bearing block 836 b of a second centering pivot arm 828 beach contact the corresponding strike plates 820 a, 820 b (along thesecond surfaces 824) to force a clockwise rotation of the foot section510 to correct the misalignment. Similarly, with particular reference toFIG. 24B, when the foot section 510 is rotated in a clockwise directionrelative to a central axis A extending through the centering fixture800, the adjustable bearing block 836 c of a third centering pivot arm828 c and the adjustable bearing block 836 d of a fourth centering pivotarm 828 d each contact the corresponding strike plate 820 c, 820 d (alsoalong the second surfaces 824) to force a counter-clockwise rotation ofthe foot section 510 to correct the misalignment.

FIGS. 25A, 25B, 25C, 25D, 25E, 25F, and 25G collectively illustrate anembodiment of the walking machine unit 500 during a series of movements.With reference to these figures, the following provides a briefstep-by-step illustration of the functionality of the centering pivotarms 828 in conjunction with the centering fixture 800 for realigningthe foot section 510 during a movement phase of the walking machine unit500.

With reference to FIG. 25A, in step 1, the lift cylinder 520 is in afully retracted position to lift the foot section 510 off the ground. Inthis position, the centering pivot arms 828 rest against the strikeplate 820 on the centering fixture 800 to maintain the foot section 510properly aligned, with the foot leveling contact surface 842 restingagainst the first surface 822 of the strike plate 820, and theadjustable bearing block 836 rests against the second surface 824 of thestrike plate 820 (see FIGS. 20-21 ).

With reference to FIG. 25B, in step 2, the lift cylinder 520 is extendedfrom its initial position in step 1 (in this embodiment, the liftcylinder extends approximately three inches). In this configuration, theadjustable bearing block 836 is no longer in contact with the strikeplate 820, as the lift cylinder 520 moves and causes the centering pivotarms 828 to pivot away from the edges of the centering fixture 800. Thefoot leveling contact surface 842 (see FIG. 21A) of the centering pivotarms 828 remains in contact with the strike plate 820 due toarticulation of the centering pivoting arms 828. In some embodiments,the pivoting movement of the centering pivot arms 828 may be due togravitational forces, or may be urged by a spring, actuator or aircylinder, a linkage, or other suitable methods. In step 2, rotation ofthe foot section 510 may begin (or be completed) if the walking machineunit 500 is being used to rotate the load being carried. In a givenwalking cycle, the walking machine unit 500 may be able to rotate thefoot section 510 (and the load being carried) by about 5° from itsinitial position.

With reference to FIG. 25C, in step 3, the lift cylinder 520 is extendedanother three inches for a total of six inches of extension. In thisconfiguration, the adjustable bearing block 836 remains out of contactwith the strike plate 820 and a smaller surface of the centering pivotarms 828 (as compared to step 2) remains contacting the strike plate820. As the lift cylinder 520 is extended, the load carried by thewalking machine unit 500 begins to be lifted off the ground.

With reference to FIG. 25D, in step 4, the lift cylinder 520 is extendedanother three inches for a total of nine inches of extension. In thisconfiguration, there is no contact between the centering pivot arms 828and the centering fixture 800, as the foot section 510 fully contactsthe ground surface. In some embodiments, the lift cylinder 520 may notneed to be fully extended to nine inches (e.g., six-inch extension asshown in step 3 is sufficient) to lift the load. The nine-inch extensionof the lift cylinder 520 may be used to provide additional clearance forthe load to accommodate a walking cycle. For example, if one of the legs55 of the oil rig 10 (see FIG. 1 ) required additional clearance toavoid rocks or other debris, then the lift cylinder 520 may be extendedto nine inches if the six-inch extension was insufficient.

With reference to FIG. 25E, in step 5, the lift cylinder 520 isretracted three inches such that the lift cylinder 520 returns to asix-inch extension. When the lift cylinder 520 retracts, the centeringpivot arms 828 again contacts the strike plate 820, where the strikeplate 820 assists in articulation of the centering pivot arms 828.

With reference to FIG. 25F, in step 6, the lift cylinder 520 isretracted another three inches such that the lift cylinder 520 returnsto a three-inch extension. In this configuration, while the foot section510 continues being lifted away from the ground, the foot levelingcontact surface 842 of the centering pivot arms 828 contacts the strikeplate 820 and begins to reduce the capture area to begin the realignmentaction.

Finally, with reference to FIG. 25G, in step 7, the lift cylinder 520 isfully retracted, thereby pulling the foot section 510 off the ground. Inthis configuration, the adjustable bearing block 836 contacts the strikeplate 820 to realign the foot section 510 against any rotationalmovement. With the centering pivot arms 828 arranged back to theirinitial position (as illustrated in step 1), the walking cycle beginagain with step 1 and so on until the walking machine system has reachedits final destination.

FIGS. 26-30 collectively illustrate another embodiment of a walkingmachine unit 1000 designed to center and accommodate for loadmisalignment during the drive operation when moving a load using thewalking machine system. The following description of FIGS. 26-30 focuseson aspects of the walking machine unit 1000 relating particularly tomanaging load alignment. Accordingly, further details regarding otherfeatures of the walking machine system (such as longitudinal or lateraldrive assemblies) may not be further discussed in detail to avoidobscuring more pertinent features of the embodiment. The followingsection provides a brief description of the walking machine unit 1000for ease of reference followed by a more detailed description ofparticular features of the walking machine unit 1000 designed for loadalignment management.

FIG. 26 illustrates an example embodiment of the walking machine unit1000 attached to a rig structure 1400, and FIG. 27 is an exploded viewof the walking machine unit 1000. With particular reference to FIG. 27 ,the following provides a brief description of various components of thewalking machine unit 1000. As illustrated in FIG. 27 , the walkingmachine unit 1000 includes a foot section 1010 having a foot plate 1011that contacts the ground surface during a walking motion of the walkingmachine unit 1000. Similar to the foot plates 111, 511 describedpreviously, the foot plate 1011 may have a generally rectangular shapewith curved ends, or may have any other suitable shape to supportmovement of the walking machine unit 1000. The foot section 1010supports one or more slide plates 1020, which may be laid flat againstthe foot plate 1011 and nested between various retainer bars 1030 of thefoot section 1010 to facilitate movement of the walking machine unit1000 in a similar fashion as described with reference to previousembodiments.

The walking machine unit 1000 further includes a roller guide assembly1040 for accommodating lateral movement of the walking machine, theroller guide assembly 1040 having similar features as the roller guideassemblies 200, 600 described previously. Similar to the previousembodiments, the lateral drive force for the walking machine unit 1000is provided by lateral drive cylinders 1050, 1060 attached along frontand rear ends of the foot plate 1011. An alternate lateral drive forcemay be provided by any suitable drive mechanism including thepiston/cylinder drive (as illustrated), jack screw drive, rack andpinion assembly, chain and sprocket drive, gear drive, electric motor,or other drive systems.

The walking machine unit 1000 further includes a longitudinal driveassembly having similar features as the longitudinal drive assembliesdescribed previously. Briefly, the assembly includes a roller assembly1070 and a pair of drive cylinders 1080, 1090 attached to the rollerassembly 1070 to drive the walking machine unit 1000 in a longitudinaldirection. The roller assembly 1070 may include the same or similarcomponents as described previously with respect to roller assembly 705,including longitudinal drive cylinders 1080, 1090 arranged in a similarfashion as described previously. It should be understood that althoughthe longitudinal drive mechanism is shown for example as a hydraulicdrive system comprising the longitudinal drive cylinders 1080, 1090,other types of longitudinal drive mechanisms may be employed such as thepiston/cylinder drive (as illustrated), jack screw drive, rack andpinion assembly, chain and sprocket drive, gear drive, electric motor,or other drive systems.

With general reference to FIGS. 26-29 , the following sectionscollectively describe components of the walking machine unit 1000designed to center or accommodate for load misalignment during the driveoperation of the walking machine system. FIG. 28 illustrates anembodiment of a centering fixture (or frame) 1100 of the walking unit1000, and FIG. 29 illustrates an embodiment of an alignment plate 1220that operates in conjunction with the centering fixture 1100 to ensurethe load is properly aligned during movement of the walking machine.With reference to FIG. 28 , the centering fixture 1100 includes a firstarm 1102 and an opposite second arm 1104 offset from one another, eachof which extending along a longitudinal axis. A first plate 1106 isattached along an end of the first arm 1102 and along an end of thesecond arm 1104, where the plate 1106 extends transversely across thefirst and second arms 1102, 1104. Similarly, the fixture 1100 includes asecond plate 1108 extending across from the first arm 1102 to the secondarm 1104, the first and second plates 1106, 1108 being offset from oneanother and extending along a horizontal axis. In this configuration,the arms 1102, 1104 and plates 1106, 1108 form a generally square-shapedor rectangular-shaped structure for the centering fixture 1100. Itshould be understood that in other embodiments, the fixture 1100 mayhave a profile other than a square or rectangular shape.

The fixture 1100 further includes a mounting plate 1110 disposed betweenthe arms 1102, 1104 and the plates 1106, 1108. The mounting plate 1110includes one or more fastener openings 1120 (e.g., bolt holes) extendingtherethrough for receiving bolts 1130 (see FIG. 27 ) to attach thecentering fixture 1100 to the roller assembly 1070 when the walkingmachine unit 1000 is assembled. As illustrated in FIG. 28 , thecentering fixture 1100 includes an opening 1140 disposed along a centralportion of the mounting plate 1110. In an assembled configuration, theopening 1110 aligns with an opening 1150 formed on the roller assembly1070 (see FIG. 27 ) to accommodate a lifting cylinder 1160 when thewalking machine unit 1000 is fully assembled. As described in previousembodiments, the lifting cylinder 1160 is used to create a lifting forceneeded to operate the walking machine and transport the load.

Returning to FIG. 28 , the fixture 1100 further includes a plurality ofalignment posts 1170, 1180, 1190, 1200, each of which extendingoutwardly relative to the plates 1106, 1108. In one embodiment, thefixture 1100 may include four alignment posts, with a pair of alignmentposts 1170, 1180 aligned along a common axis extending through the firstarm 1102 such that the alignment post 1170 is positioned adjacent afirst end of the first arm 1102 and the alignment post 1180 ispositioned adjacent an opposite second end of the first arm 1102.Similarly, the second pair of alignment posts 1190, 1200 are alignedalong a common axis extending through the second arm 1104 in a similararrangement as described previously with respect to the alignment posts1170, 1180.

The configuration of the alignment posts 1170, 1180, 1190, 1200described above can be achieved in any one of various suitable designs.For example, in one embodiment, the alignment posts may be formed asintegral components of the respective arms 1102, 1104. In one suchembodiment, the arms 1102, 1104 may be sufficiently long such that aportion of the arm shaft extends outwardly and beyond the mountingplates 1106, 1108 when coupled, thereby forming the adjustment postsdescribed previously. To accommodate this design, the mounting plates1106, 1108 may each include openings (not shown) through which the arms1102, 1104 receive the mounting plates 1106, 1108. Once the mountingplates 1106, 1108 are secured, a portion of the arms 1102, 1104 extendsthrough the openings and protrudes beyond the mounting plates 1106,1108, thereby forming the alignment posts illustrated in FIG. 28 .

In other embodiments, the alignment posts 1170, 1180, 1190, 1200 mayinstead be separate components apart from the arms 1102, 1104. In suchembodiments, the alignment posts may be threaded into or otherwisesecured to either the mounting plates 1106, 1108 or the arms 1102, 1104in various suitable designs. In still other embodiments, the alignmentposts 1170, 1180, 1190, 1200 may be formed in different configurationswithout departing from the principles of the disclosure.

In some embodiments, the alignment posts 1170, 1180, 1190, 1200 may bewrapped with a durable, wear resistant cover 1210 (see FIG. 27 ) orother suitable protective material to increase the durable life of thealignment posts and to facilitate repair when needed. In otherembodiments, the alignment posts may not have a cover and instead bemade of durable materials themselves.

FIG. 29 illustrates an example embodiment of an alignment plate 1220 ofthe walking machine unit 1000 that operates in conjunction with thealignment posts 1170, 1180, 1190, 1200 to ensure proper load alignment.The ensuing section provides details of the alignment plate 1220,followed by a brief description of the functionality of the alignmentposts 1170, 1180, 1190, 1200 and the alignment plate 1220 within thewalking machine unit 1000.

With reference to FIG. 29 , the alignment plate 1220 is a general planarstructure having a header end 1230, an opposite footer end 1240, andperipheral sides 1250, 1260. The front and rear surfaces of thealignment plate 1220 include a plurality of openings 1270 extendingtherethrough, the openings 1270 designed for receiving fasteners 1280therethrough affix the alignment plate 1220 in position (see FIG. 26 ).As illustrated in FIG. 29 , the footer end 1240 of the alignment plate1220 includes notches 1290, 1300 formed thereon. The notches 1290, 1300each include slide surfaces 1310, 1320 that lead toward a seat 1330,1340 at the uppermost region of the notches 1290, 1300. Preferably, theseat 1330, 1340 has a surface profile designed to correspond with theexterior profile of the adjustment posts 1170, 1180, 1190, 1200. Forexample, in the illustrated embodiments, the adjustment posts 1170,1180, 1190, 1200 are circular, and the seats 1330, 1340 are curved witha radius matching that of the circular adjustment posts 1170, 1180,1190, 1200 to ensure proper engagement. As further described in detailbelow, the notches 1290, 1300 on the alignment plate 1220 and thealignment posts 1170, 1180, 1190, 1200 on the centering fixture 1100operate together to center and align the load being transported on thewalking machine units 1000.

With collective reference to FIGS. 26 and 29 , the following sectionprovides a description of the functionality of the alignment posts 1170,1180, 1190, 1200 and the centering fixture 1100 within the walkingmachine unit 1000. Although reference in the following description ismade to operation of only one pair of adjustment posts 1170, 1190, itshould be understood that the walking machine unit 1000 typicallyincludes multiple such posts (e.g., two on each of a front side and arear side of the machine walking unit 1000) each operating in the samegeneral fashion. Accordingly, it should be understood that the ensuingdescription applies equally to all such adjustment posts.

An example operation of a walking machine unit 500 and lifting cylinder520 was previously discussed with reference to FIGS. 25A, 25B, 25C, 25D,25E, 25F, and 25G. With reference to walking machine unit 1000 of FIGS.26-29 , the lifting cylinder 1160 and walking foot section 1010 operatein a substantially similar fashion. In other words, the lifting cylinder1160 cycles through various extended positions to lift the foot section1010 off the ground and move the load. The following description focusesprimarily on the interaction of the alignment posts 1170, 1180, 1190,1200 and the alignment plate 1220.

During the walking operation, the alignment plate 1220 is raised awayfrom the centering fixture 1100 such that the alignment posts 1170, 1190are not in contact with the notches 1290, 1300. As the walking operationcontinues, the alignment plate 1220 is brought together toward thecentering fixture 1100. When the load is properly aligned, the alignmentposts 1170, 1190 of the centering fixture 1100 are seated in the seats1330, 1340 of the respective notches 1290, 1300 to maintain the footsection 1010 in a proper, level position. FIG. 29 illustrates anoccasion when the foot section 1010 is not in proper position. Withreference to FIG. 29 , the alignment posts 1170, 1190 are positionedagainst the slide surfaces 1310, 1320, respectively. From this position,the angled slide surfaces 1310, 1320 guide the adjustment posts 1170,1190 toward the seats 1330, 1340, thereby shifting the foot section 1010into proper position. In some embodiments, the centering fixture 1100and alignment plate 1220 may shift the foot section 1010 by up to 5°. Inother embodiments, larger or smaller corrections may be made. With theload centered, the walking operation continues on its next cycle untilthe load is transported to its desired position.

FIG. 30 is a top perspective view of a walking machine system accordingto an example embodiment, with four walking machine units 1100, onedisposed at each of the four corners of a rig structure 1400. It shouldbe understood that in other embodiments, more or fewer walking machineunits 1100 may be used depending on various factors, such as size andweight of the load.

Other embodiments are envisioned. Although the description abovecontains certain specific details, these details should not be construedas limiting the scope of the invention, but as merely providingillustrations of some embodiments/examples. It should be understood thatsubject matter disclosed in one portion herein can be combined with thesubject matter of one or more of other portions herein as long as suchcombinations are not mutually exclusive or inoperable.

The terms and descriptions used herein are set forth by way ofillustration only and not meant as limitations. It will be obvious tothose having skill in the art that many changes may be made to thedetails of the above-described embodiments without departing from theunderlying principles of the invention.

The invention claimed is:
 1. A walking machine system for moving a load relative to a ground surface in one or more incremental steps via a plurality of lift assemblies, each lift assembly comprising: a lift mechanism operable to lift a load-bearing frame supporting the load; a foot pad assembly including a foot plate contacting the ground surface; a centering frame supported by the foot pad assembly, the centering frame including one or more centering members; and an alignment structure in operable communication with the centering frame, the alignment structure cooperating with the one or more centering members of the centering frame to align the foot pad assembly during transport of the load.
 2. The walking machine system of claim 1, wherein the one or more centering members of the centering frame includes a strike plate having a first contact surface and a second contact surface, the alignment structure further comprising a pivot arm coupled to the lift mechanism and movable therewith, the pivot arm having a contact surface thereon and further including a bearing block coupled thereto, wherein the contact surface of the pivot arm contacts the strike plate along the first contact surface to level the foot pad assembly.
 3. The walking machine system of claim 2, wherein the bearing block contacts the strike plate along the second contact surface to rotationally align the foot pad assembly relative to a central axis of the centering frame.
 4. The walking machine system of claim 2, wherein the strike plate includes a substantially L-shaped structure, wherein the first contact surface and the second contact surface are substantially orthogonal to one another.
 5. The walking machine system of claim 2, wherein the contact surface of the pivot arm is curved.
 6. The walking machine system of claim 2, wherein the pivot arm pivots relative to the lift mechanism as the lift mechanism is moved from a first position to a second position.
 7. The walking machine system of claim 6, wherein during the first position, both the contact surface and the bearing block of the pivot arm contact the respective first and second contact surfaces of the strike plate, and wherein during the second position, the bearing block is free of contact from the strike plate.
 8. The walking machine system of claim 1, further comprising a translation assembly coupled to the lift mechanism and the foot pad assembly, the translation assembly comprising: a longitudinal drive assembly supporting the lift mechanism and operative for translating the lift mechanism and the load along a longitudinal direction; and a lateral drive assembly supporting the longitudinal drive assembly and operative for translating, independently of the longitudinal drive assembly, the longitudinal drive assembly, the lift mechanism and the load along a lateral direction.
 9. The walking machine system of claim 8, further comprising: a first and second slide plate each disposed on a top surface of the foot pad assembly, wherein the longitudinal drive assembly includes a roller assembly; a track housing for supporting the roller assembly and a longitudinal drive cylinder system for moving the roller assembly longitudinally along the track housing; and a lateral drive system for moving the track housing laterally in a sliding motion across the first and second slide plates.
 10. The walking machine system of claim 9, wherein the first and second slide plates are laterally offset from one another and each contact a portion of the foot plate, the first and second slide plates each nesting between a plurality of retaining elements connected to the slide plate in a free-floating condition flat against the foot plate.
 11. The walking machine system of claim 8, wherein the lateral drive assembly comprises a hydraulic piston and cylinder drive system.
 12. The walking machine system of claim 8, wherein the lateral drive assembly comprises a drive system selected from the group consisting of: hydraulic piston and cylinder drive, jack screw drive, rack and pinion assembly, chain and sprocket drive, gear drive, electric motor drive.
 13. The walking machine of claim 1, wherein the centering frame further includes a central opening through which the lift assembly mechanism extends.
 14. The walking machine system of claim 1, wherein the alignment structure includes an alignment plate coupled to the lift mechanism, the alignment plate including a first notch formed thereon, the first notch having a slide surface and a seat.
 15. The walking machine system of claim 14, wherein a first one of the one or more centering members cooperates with the slide surface of the first notch, the slide surface guiding the centering member toward the seat of the first notch to align the foot pad assembly during transport of the load.
 16. The walking machine system of claim 15, the alignment plate including a second notch formed thereon, the second notch spaced apart from the first notch and having a slide surface and a seat, and wherein a second one of the one or more centering members cooperates with the slide surface of the second notch, the slide surface guiding the centering member toward the seat of the second notch to align the foot pad assembly during transport of the load.
 17. The walking machine system of claim 1, wherein the one or more centering members of the centering frame includes one or more adjustment posts, each extending outwardly from the centering frame and cooperating with the alignment structure to align the foot pad assembly during transport of the load.
 18. The walking machine system of claim 17, further comprising a removable wear cover coupled to each of the one or more adjustment posts, wherein the removable wear cover contacts the alignment structure during transport of the load.
 19. The walking machine system of claim 1, wherein the alignment structure is coupled to the lift mechanism for movement therewith, the lift mechanism driving movement of the alignment structure relative to the centering frame such that the alignment structure is cyclically moved into and out of engagement with the one or more centering members of the centering frame during transport of the load.
 20. The walking machine system of claim 14, wherein the slide surface of the first notch of the alignment plate is an angled slide surface, and wherein the alignment plate and the one or more centering members of the centering frame cooperate to align the foot pad assembly by up to 5° during transport of the load. 